Battery operated communication devices are well known in the art. Such devices may comprise, for example, cellular telephones, personal digital assistants, digital cameras, digital camcorders or even laptop computers. As such devices have evolved, the quantity and quality of information, particularly audio and/or video information, that may be recorded on such devices has dramatically increased. For example, it is quite common for current digital camcorders to have the capacity to store hours worth of audio and video information.
With the increased capability of such devices, there's has been a commensurate increase in the power and storage demands placed upon such devices. That is, in order to provide the improved performance characteristics, for example, the amount of processing or computing power available in such devices has been commensurately increased. As a result, greater power consumption occurs. To address this situation, longer lasting batteries having greater storage capacity have been created. However, there are limits to the improvements available through battery technologies. Other techniques are necessary if battery operated devices are to be able to keep up with the power demands of ever more capable user applications.
Other techniques for reducing power supply consumption in battery operated devices are known, particularly for devices that perform encoding of various media types. For example, U.S. Pat. No. 6,493,326 discloses a technique which lowers the encoding rate of a variable rate voice coder in response to reduced voice activity by a user of the device. In this manner, the circuitry necessary to transmit the voice data is energized less frequently, thereby resulting in reduced power consumption. In a similar vein, Japanese Published Patent Application No. 2000-174696 teaches a system in which the voltage of a battery is monitored to determine when the voltage falls below a certain threshold. When this occurs, the rate of voice encoding is decreased, e.g. to half rate or less, such that the time required to transmit voice data is similarly decreased. Once again, power consumption of the battery operated device may be reduced. Further still, Published Japanese Patent Application No. 2000-069556 describes a system in which an encoding rate upper limit for a voice encoder is set by a user of the device. When a power saving mode is entered, preferably through actuation of a input mechanism by a user of the device, the encoding rate of the voice encoder is limited by the previously established upper limit. Each of the above-described techniques limits power usage by reducing the rate of encoding activities performed by the battery operated device. However, the above-described references do not address the situation where the battery operated device additionally records the encoded information.
With further regard to recording information, the quantity of recorded information that may now be stored on battery operated devices has risen significantly in recent years, due in part to the improved capacity of memory or storage devices. Notwithstanding this improvement, the demand to be able to record ever increasing quantities of information on battery operated devices has not abated. For example, current digital camcorders allow users to select different encoding modes that provide different qualities of recorded information. Typically, lower quality encoding provides the opportunity to record more information; higher quality encoding provides less opportunity to record information. Regardless, the ability to select encoding (quality) levels is typically done at the beginning of a recording session, and encoding proceeds at the selected level throughout the recording session. It would be advantageous to provide a technique that addresses the need for controlling power consumption in battery operated devices while simultaneously providing greater control over recording quality selection and, hence, memory usage. It would be further advantageous to provide a technique that addresses the need for controlling power consumption in battery operated devices while decoding recorded information.